U.S. Pat. No. 3,342,124 (Apparatus For Dewatering and Rinsing Hydrous Substances) discloses a squeezing apparatus comprising two corotating drums: an inner perforated rotary drum which rotates within a larger outer perforated rotary drum to form a single nip zone. Neither drum is heated, nor is a film formed of the hydrous material, preferably a fiber pulp suspension, being treated. In contrast, the present invention involves the combination of a rotating perforated drum in tangential relationship with at least two non-rotating stators or relatively stationary bodies, in various forms, in order to form at least two nip zones.
U.S. Pat. No. 3,484,213 (Polymer Handling and Conveying Apparatus) discloses a continuous polymerizer with a single rotating radially perforated annular cylinder that is eccentrically located within a heated housing to form a single nip zone. The apparatus serves to devolatilize a polymer melt by creating honeycombed films of great surface area to facilitate removal of gaseous reaction byproducts. In contrast with the present invention, a single perforated cylinder or drum is employed in association with only a single nip zone.
U.S. Pat. No. 4,029,459 (Method and apparatus for Manufacture of Granulates from Pulverulent, Granular, Doughy or Similar Material) discloses a method of forming granulates by means of a hollow perforated drum with a plurality of helical surfaced rollers, to form nip zones within the drum interior. In contrast to U.S. Pat. No. 4,029,459, however, the present invention, when operating with a single rotary perforated drum, forms nip zones on either side of the perforated drum such that the fluid being processed can move repeatedly inside and outside of the rotating perforated drum as it axially progresses along the apparatus, for example, from an inlet to an outlet when operating on a continuous basis.
U.S. Pat. No. 4,189,291 (Apparatus and Process for Recovering Scraps of Thermoplastic Material Even of Heterogeneous Shapes, by Gradual Melting and Compression Through One or More Orifices) discloses a rotating, non-perforated, heated cylinder eccentrically located within a stationary heated cylindrical casing to form a single nip, for plasticizing or softening solid thermoplastic materials that are fed to it through a hopper. Thus, this patent does not disclose an apparatus involving a rotary perforated drum or cylinder that forms at least two nip zones within the housing.
The present invention is directed to an improved method and apparatus which employs a rotating perforated drum in a novel arrangement in order to mix or otherwise process liquids with greater efficiences of both time and energy. Such an improvement is frequently desirable for carrying out many industrial and chemical processes.